1. Field of the Invention
The invention relates to methods and apparatus for inspecting turbine engine rotor thru-bolts and their corresponding rotor disc cavities. More specifically, embodiments of the invention are directed to camera inspection apparatus and methods for inspecting thru-bolt male threads, thru-bolt outer circumference and the corresponding mating rotor disc cavity walls of a combustion turbine compressor or turbine section rotor. Embodiments of the invention facilitate creation of composite side-by-side images of the disc cavity wall and mating thru-bolt outer circumference as well as the bolt male threads profiles, for example to determine future serviceability during turbine engine maintenance.
2. Description of the Prior Art
Known turbine engines have rotors comprising a plurality of serially aligned rotor discs with a circumferentially spaced array of axially aligned rotor disc cavities. The rotor discs are axially retained by thru-bolts that are inserted in the axially aligned disc cavities from one axial end of the rotor. Referring to the combustion turbine engine 20 of FIG. 1, the compressor section rotor 22 has four rotor discs 24 that are retained by thru-bolts 26 and mating nuts 28 on both ends of the bolt. During periodic maintenance outages the rotor 20 is inspected for serviceability. During rotor service the rotor disc 24 and thru-bolt 26 interfaces are visually inspected after rotor disassembly. The thru-bolts 26 male threads that mate with the nuts 28 and the bolt outer circumference are inspected for conformity with component specifications. Similarly the disc 24 cavities that receive the thru-bolts 26 are visually inspected with a bore scope. During visual inspection portions of the thru-bolts 26 and disc 24 cavities may be photographed for remote inspection by others and for archival purposes.